In a large bowl or container with a lid, stir chili-garlic sauce, hoisin, sesame oil, and 2 Tbsp. soy sauce. Season steak with 1 ½ tsp. salt and sprinkle with baking soda, then toss to coat. Transfer to bowl and toss again to coat. Cover and marinate at least 2 hours and up to overnight.

In a small saucepan over medium-high heat, cook white scallion parts, ginger, garlic, honey, vinegar, and remaining ¼ cup soy sauce, stirring, until sauce is very thickened and reduced to a few tablespoons, about 10 minutes; season with salt, if needed. Let cool. If sauce cools for too long, add 1 to 2 tsp. water and return to heat to loosen.

Meanwhile, in a large bowl, toss onion and ½ tsp. salt. Drizzle with 1 Tbsp. neutral oil and toss to combine, separating layers of onion pieces so that each piece is only 1 to 2 layers thick.

Alternate threading steak and onion pieces onto skewers, using 4 to 5 pieces of steak per skewer (for an 8" skewer, feel free to use more pieces).

Prepare a grill for medium heat; preheat 5 minutes (or heat a grill pan over medium heat). Grease grates or pan with neutral oil.

Grill skewers, rotating 90° every 2 to 3 minutes and brushing with some sauce during the last minute, until steak reaches desired degree of doneness, 8 to 10 minutes.

Spread rice onto a platter. Top with skewers, then brush with any remaining sauce. Top with green scallion parts and sesame seeds; season with salt, if needed.